President Mohammed Morsi is unlikely to worry if Egypt's Islamist-leaning draft constitution passes by only a small margin in a December 15 referendum, since he and his backers tout his 51 perc ent election victory in June as a "popular mandate" that is beyond any challenge.

Still, an idea taking root among many secular Egyptians is that a constitution requires a reasonable degree of consensus to qualify as a charter for all - and that it is fundamentally illegitimate to ram one through by a simple majority despite opposition from key sectors of society that oppose giving religion such a major role in the affairs of state.

"It is irrational to have a constitution that does not genuinely represent everyone," said Kahlil al-Anani, a British-based expert on Egypt. "It is important that a constitution is passed with a comfortable majority, but it does not make the document less credible if it is a modest majority."

The proposed constitution is at the heart of the nation's worst political crisis since the overthrow nearly two years ago of authoritarian President Hosni Mubarak. The charter has divided Egypt, with Morsi and his Islamist backers, including ultraconservative Salafis, in one camp, and secularists and leftists, including minority Christians and women, in the other.

At least six civilians have been killed in street clashes and several offices of the president's Muslim Brotherhood torched in the unrest.

With such deep polarization, Morsi on Saturday offered the opposition a mixed bag: He rescinded decrees he issued November 22 that gave him near absolute powers, but he insisted the referendum go ahead as scheduled.

The opposition's response was to call for more street protests to try to force him to abandon the draft constitution.

There may only be a small chance of Morsi doing that.

Islamists from the Muslim Brotherhood and other like-minded groups are already campaigning for a "yes" vote, marketing the referendum and the adoption of a constitution as the door to stability and economic recovery. If adopted, elections for parliament's lawmaking lower chamber - dissolved by a court ruling in June - must be held within two months.

The opposition's apparent despair over whether it can stop the referendum from going ahead is deepening the schism between Islamists and non-Islamists. Many Egyptians worry it will produce a constitution that is far from representative of the country's 85 million people.

Critics say Egypt is approaching the referendum with a heavy heart rather than the jubilation that supposedly accompanies an occasion that, at least in theory, should be a milestone in the shift from authoritarian rule to democracy.

"This is a constitution that will not contribute to stability," said prominent rights lawyer Negad Boari. "The president wants the referendum, regardless of the cost. They are creating a religious state that they had long dreamt of and waited for. It is now within reach."

The question of whether to rally a "no" vote" or boycott the referendum is a challenging one for the opposition as it comes under scathing criticism as isolated and motivated by its refusal to accept the position of power gained by the Islamists following a string of electoral wins since Mubarak's ouster in February 2011.

Islamists accuse the opposition of being - knowingly or not - part of a conspiracy by Mubarak loyalists to destabilize Egypt and derail its transition to democratic rule.

An opposition spokesman told a news conference Sunday that it is "completely rejecting" the referendum and would not accord legitimacy to a charter that will further divide the nation. But there was no word whether the opposition was calling for a boycott or urging supporters to cast a "no" vote.

The ambivalence may be a reflection of divisions in the ranks of the opposition. None of its main leaders addressed the news conference.

Urging a "no" vote would give the referendum legitimacy, especially if the draft is passed, as expected. Only a simple majority is needed for adoption.

A boycott would allow the opposition to claim the vote was illegitimate, especially if staying away from the polls significantly reduces turnout.

Not everyone is convinced, however, that the discipline and commitment of the hard-core Islamist voters would deliver the victory Morsi wants, citing his narrow win in June and the 25 per cent of the vote he received in the presidential election's first round, when he ran in a field of 13 of mostly Islamist candidates.

But Morsi, the chief proponent of the document, may have succeeded in the past two weeks in rallying firmly behind him the entire spectrum of Islamist groups, not just his relatively moderate Muslim Brotherhood.

"He faced the choice of losing his credibility or his popularity. He went for the latter," said al-Anani, alluding to Morsi's repeated promises in his early days in office that he would never put the constitution to a vote unless it enjoyed consensus.

The problem with the constitution began months before the current political crisis.

The predecessor of the panel that drafted the charter was dissolved when a court ruled that it was not inclusive enough. Similarly, the second one was dominated by Islamists, and the same court was widely expected to dissolve it in a session scheduled for December 2.

In anticipation of such a ruling, the panel - packed with Morsi supporters and chaired by an Islamist - held an all-night session on November 29-30 to adopt the document, voting overwhelmingly in favor of each of its 234 clauses.

Many Egyptians watched the session televised live with a mix of bemusement and horror as the chairman, career judge Hossam al-Ghiryani, doggedly pushed the members to finish, badgering some of them for wasting time arguing some of the clauses. In the session's final hours, several new articles were hastily written and added to resolve lingering issues. On December 1, Al-Ghiryani gave the document to Morsi, who then called for the December 15 referendum.

But the Islamists' job was not done.

They are now using their time-honored tactic of employing religion to influence the vote. That tactic was widely used in a March 2011 referendum on a constitutional declaration that the Islamists supported and again in the election for both chambers of parliament.

They say a "yes" vote is one for God, Islam and the faithful. A "no" vote is portrayed as being against them.

The draft constitution largely reflects the conservative vision of the Islamists, with articles that rights activists, liberals and others fear will lead to restrictions on women and minorities, as well as on civil liberties in general.

One article underlined that the state will protect "the true nature of the Egyptian family ... and promote its morals and values" - phrasing that suggests the state could intervene to prevent anything deemed a threat to families.

The draft also says citizens are equal under the law, but an article specifically establishing women's equality was dropped because of disputes over the phrasing.

A new article added to the customary mention that "principles of Islamic law" provide the basis of legislation points to theological doctrines and their rules, wording that could give Islamists the tool for insisting on stricter implementation of Shariah rulings.

Another new article states that Egypt's most respected Islamic institution, Al-Azhar, must be consulted on any matters related to Shariah. Critics fear that measure will lead to legislative oversight by clerics.

"This is not the constitution that will turn the page and usher in a new Egypt," said Hossam Bahgat, a legal expert and human rights lawyer. "The issue of the constitution will continue to be on the political agenda of Egypt with persistent calls to replace it with a more balanced one."